1. Field of Invention
The present invention relates to an image processing circuit and an image processing method. More particularly, the present invention relates to an image processing circuit and an image processing method that perform an image sharpening operation.
2. Description of Related Art
When a video is played, color and tone are not the only characteristics that draw observers' attention. Edges, which define the shapes of objects in the video, also attract observers' attention. Image processing is a kind of operation that enhances those video characteristics and improves or emphasizes visual effects of the video. For example, post procedure can make images captured by digital cameras or scanners become clearer and more colorful.
Sharpening operation is an important image processing technique. “Sharpness” is a term that people frequently use to indicate a contract ratio. After sharpening the edges of an object in an image, the image's contrast ratio increases, and the object becomes more conspicuous. After performing a sharpening operation on an original image to generate a sharpened image, observers generally deem that the sharpened image is clearer than the original image.
The sharpening operation can enhance the edges of the objects in the images. However, it can also result in some undesired visual effects. For example, in a border area between different colors, such as between white cloud and blue sky, sharpening operation may generate discernible halo and decrease the visual quality of the image.